Hemocatharsis including hemodialysis, hemofiltration, etc. are employed at present as apothanasia for patients of chronic renal insufficiency, and the number of patients in our country to whom hemocatharsis is applied already exceeds 100,000. The principle of hemocatharsis resides in contact of blood with a dialyzing liquid through a thin membrane thereby eliminating spodogen and metabolites by diffusion into the dialyzing liquid and also removal of excess water by utilizing difference in hydraulic pressure. In case hemocatharsis is to be carried out, a hemocathartic vessel is used where a blood circuit made of a bundle of hollow fibers is accommodated in a housing to have a structure wherein blood flows inside the hollow fibers while the dialyzing liquid flows outside the hollow fibers.
An anti-coagulant such as heparin has hitherto been continuously administered in case of hemocatharsis with a view of inhibiting coagulation reaction of blood in the hemocathartic vessel. Now that long-term apothanacia as long as 20 years has become possible according to an improvement in elimination performance of solutes in the hemocathartic vessel, problems caused by the use of heparin are successively pointed out. In particular, hepatic disorder, such as lipid metabolism abnormality, elongation of bleeding time or allergic reactions due to the administration of heparin for a long period of time, is recognized to be side effect for patients. From these viewpoints, development of a biocompatible material is demanded which is so excellent in blood-compatibility that coagulation of blood is not caused by a little or no use of an anti-coagulant in case of hemocathartic therapy.
As an attempt to improve blood-compatibility of cellulose hollow fibers, for example, reports have been made regarding inhibition of activation of complements contained in cellulose membrane materials due to a method for covalently bonding a hydrophilic high polymer such as polyethylene oxide to the surface of the fibers or a method for treating the surface with a high polymer containing tertiary amino groups, etc. However, it is difficult to inhibit coagulation of blood in such hollow fibers so that administration of a large amount of an anti-coagulant becomes eventually necessary. Thus, development of such a substance itself is demanded which is furnished with both affinity to cellulose as a base and biocompatibility.
It is an object of the present invention to provide a novel water-soluble cellulose derivative possessing both biocompatibility and affinity to cellulose.
It is another object of the present invention to provide a biocompatible material which is excellent in biocompatibility and utilizable for hemocathartic vessels and the like.